Development and application of infrared and tracer-based planar laser-induced fluorescence imaging diagnostics

Two different planar laser-induced fluorescence (PLIF) diagnostics have been developed and refined. The first diagnostic, infrared-PLIF for temperature and pressure, utilizes infrared (IR) excitation of small molecules, such as CO, CO2, and H2O, and collection of the subsequent vibrational fluorescence. The second diagnostic, tracer PLIF for simultaneous mole fraction and temperature, utilizes UV excitation and collection of fluorescence from a tracer species (3-pentanone) in the near-UV and visible spectrum.; IR-PLIF measurements of temperature and pressure are a new application of the technique. Initial IR-PLIF measurements focused on species concentrations of CO and CO2. The strong dependence of IR-PLIF signals on temperature and pressure indicated that IR-PLIF measurements of those quantities are possible.; Methods for calculating the absorption cross section and fluorescence quantum yield for infrared laser excitation of small molecules (diatomics and triatomics) are developed to study the temperature and pressure dependence of the fluorescence. An experimental study of IR fluorescence from CO + N 2 mixtures at room temperature conditions is used to evaluate the level of modeling complexity needed to accurately estimate the time-dependent vibrational populations used to calculate the fluorescence quantum yield. A model for the non-local influence of fluorescence radiative trapping is presented and used to estimate the reduction in signal due to trapping as a function of environmental conditions.; Diagnostics for temperature and pressure are developed using the models for absorption cross section, fluorescence quantum yield, and radiative trapping to guide the implementation. A two-line temperature diagnostic capable of measurements in flows with nonuniform pressure and species concentrations is derived from the model results. A slightly altered two-line technique utilizing offset excitation on one of the rotational lines allows for measurements of pressure in flows with nonuniform temperature and species concentrations. Compressible flow fields are an ideal environment for these diagnostics, applied here to imaging an under-expanded jet of CO2 and N2. The demonstration results illustrate the power of these new diagnostics and the feasibility of single-shot measurements of temperature and pressure in compressible flows using IR-PLIF.; The second diagnostic studied, tracer PLIF measurements for simultaneous mole fraction and temperature, involves the selection of a diagnostic for mole fraction measurements and optimization of the diagnostic for use in IC engines. The target of the mole fraction measurements is the distribution of exhaust gas residuals (EGR) present in IC engines. A tracer-based method for measuring EGR is developed using negative-PLIF (N-PLIF) of 3-pentanone seeded into the intake air and fuel of an IC engine.; To eliminate the influence of temperature on the N-PLIF measurements, a simultaneous temperature measurement strategy is selected. An uncertainty analysis is used to select optimal excitation wavelengths for simultaneous imaging of EGR and temperature. The selection process and testing of equipment for the diagnostic is described in detail. Validation of the tracer-based PLIF measurements are performed in an IC engine and measurements under homogeneous in-cylinder conditions are used to tune the 3-pentanone fluorescence quantum yield model and to estimate the accuracy and precision of the optimized diagnostic.; Demonstrations of the diagnostic are performed in an optical IC engine under fired homogeneous-charge compression-ignition (HCCI) operation and under HCCI operation with large negative valve overlap (NVO) and direct injection of fuel during the NVO period. The results validate the ability of the diagnostic to acquire high quality single-shot images of temperature and EGR mole fraction under harsh in-cylinder conditions with highly stratified EGR and temperature distributions. The measurements...